Bottles and jars are made by blowing air into glass. Today, bottles and jars are mass produced using machinery. To make a jar, molten glass is dropped into a mould which has a plunger attached to it. The plunger is used to press the rough shape of the jar. The jar is then finished in a second mould by blowing. Bottles cannot be shaped using a plunger because they have a narrow neck. Instead the glass is blown at both stages.
A big modern bottle machine has a number of moulds operating at the same time. Some factories can make up to 12,000 bottles an hour. As with all glass, bottles must be annealed before they can be used.
Glass bottles are now mass produced in factories where they are quicker and cheaper to make.
Making a bottle
A lump of molten glass, known as a gob, drops into the first mould which is upside down
(1). The bottom of the mould is the exact size of the neck of the bottle with a plug in the centre. Air is blown in at the top so that the glass is pushed down into the mould to form the neck
(2). The plug at the bottom is removed. Next a plate is fixed over the top of the mould. More air is blown in from the bottom to form the rough shape, or parison
(3). The parison is removed, turned over and placed in the second mould
(4) Where the final shape is blown
(5). The bottle is now ready for annealing
(6). When the bottle has cooled, it is stacked and stored, ready to be filled.
Picture Credit : Google